As a general rule no but rewards vs numbers / challenge will be a factor I.e a big party will have less trouble dealing with some pits therefore not gain as much xp per person as a small group in an equivalent pit. General guidance 4-8 makes for a good ‘pit’ group, and having a total group that is larger than this is your choice. However, there may be some pits which do restrict access through needed skills / xp requirements / xp limits.